What does it mean to subtract 8 from the first number in the front of the train when it starts to do math problems? I can't understand the topic.
Let me answer your question. When the small train starts, it starts from the first number and subtracts 8 from each number in turn. The results are written in the corresponding line below. For example, 1 1-8= (), 16-8= (), and the following questions are the same. Write the calculated results in the corresponding lines with 12+4, 15+4 and 9+4 in turn.